Sail shape control device

ABSTRACT

A sail control device for flattening the after portion of a triangular sail. The sail control device includes at least one tensioning member which extends from a front portion of the sail across the sail to the after portion of the sail. The tensioning member may be attached to a Cunningham line for tensioning.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority of U.S. Provisional Patent ApplicationSer. No. 61/294,733 filed Jan. 13, 2010, which is incorporated herein byreference.

FIELD OF THE INVENTION

The invention relates to a device for use in controlling the shape of asail.

BACKGROUND OF THE INVENTION

Sails are used to propel craft such as sailing vessels, sailboards,wheeled land sailers and the like. The sails are airfoils which functionlike an airplane wing to create lift and drag force to propel thevessel. Sails are designed to have a desired shape and to maintain thatshape through a range of wind speeds. It is also desirable for the sailsto be lightweight and durable. In the past sails have been formed ofpanels of material such as canvas or Dacron. Current high-performancesails are formed by laminating load-bearing materials such as Kevlar,carbon fiber, or Vectran between layers of film such as Mylar. Despitethe use of these techniques, it is frequently desirable to alter theshape of the sail for power or lift in accordance with the sailing angleor wind speed. Current controls include tensioning the tuff of a sailwith a Cunningham, the foot of the sail with an outhaul, or changing thebend or shape of a mast supporting the sail. The Cunningham typicallyincludes a ring which is spaced upwardly from the tack or clew of a sailand tensioning device such as a strap or line with a purchase which arepulled downwardly to move the eye toward the tack or clew to tension theluff of the sail. The bending of the mast flattens the mainsail bypulling the luff curve out of the sail making the sail much flatter.However, when the sail gets flat in the forward portion, the rearportion of the sail towards the leech falls off to the leeward side ofthe sail.

It would be desirable therefore to provide a sail control which wouldflatten the main without resulting in having the rear or exit of thesail fall off to leeward.

SUMMARY OF THE INVENTION

The invention relates to a sail control device on a sailboat, inparticular for triangular sails having a head, tack and clew and a mainbody portion. The sail control device includes at least one flexibletensioning member which extends across the body of the sail and attachesto an after portion of the sail. The tensioning member is slidable alongthe body to change the shape of the after portion of the sail. One ormore of the flexible members may be mounted to a batten pocket or leech.In the preferred embodiment, the at least one tensioning member is aplurality of flexible members radiating from the forward portion of thesail to the after portion of the sail. The plurality of flexible membersare mounted in tubes which are affixed to the outer surface of the bodyof the sail. In another embodiment the tensioning members are sandwichedbetween outer layers of material forming the outer surfaces of alaminated sail. The forward ends of the tensioning members may bemounted to a Cunningham line. Movement of the Cunningham and tensioninglines results in a change of shape in the after portion of the sail.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view of a sail control device in place on a jib andmain of a sailboat in accordance with the invention;

FIG. 2 is a perspective view of a mainsail taken from the cockpit of asailboat showing the change in shape occurring when the sail controldevice is tensioned in accordance with the invention;

FIG. 3 is a cross-sectional view of a sail showing a line movablebetween outer layers of the sail;

FIG. 4 is a cross-sectional view of a sail showing a flexible memberinside a tube which is positioned between outer layers of the sail;

FIG. 5 is a partial side view of a sail showing a line affixed to aleech tape of the after portion of the sail;

FIG. 6 is a side view of an after end of the line attached to a forcespreading device affixed to the leech of the after portion of the sailin accordance with the invention;

FIG. 7 is a side view of a portion of a front part of the sail showing aCunningham and tack;

FIG. 8 is a side view of a mainsail showing lines extending along thecurvature of the sail;

FIG. 9 is an adjustment device for adjusting the individual lines inaccordance with the invention;

FIG. 10 is a cross-sectional view of a mainsail showing a tensioningmember mounted to an outer surface of a sail;

FIG. 11 is a cross-sectional view of a mainsail showing a tensioningmember mounted within a sleeve; and

FIG. 12 is a cross-sectional view of laminated panels and a tensioningmember.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

As shown in FIG. 1, a sail control device 10 for a sailboat includes atleast one tensioning member 12 which is attached to an after or rearportion 14 of the sail. When the tensioning member 12 is tensioned, therear portion 14 of the sail adjacent a leech is flattened. The afterportion 14 is tensioned to prevent the exit of the sail from falling offto leeward to improve the performance of the sailboat 16.

The sail control device 10 is shown in FIG. 1 on a mainsail 18 or jib 20as shown in FIG. 1. However, the sail control device may be used on anytriangular fore and aft sail such as a main, jib, or stay sail. However,the construction and operation will be discussed herein only withrespect to the mainsail 18. The main sail 18 has a head 22, a tack 24 ata forward lower corner portion 26 of the mainsail, a clew 28 at theafter portion of the foot of the sail, and a main body 30 with rearportion 14. The sail may also be provided with a Cunningham. TheCunningham is a device which places tension on a luff 32 of the sail.The Cunningham includes a line 34 which extends through a ring 36mounted in the lower corner portion 26 of the sail slightly above thetack 24. One end of the line 34 is secured to a tack fitting or eye 38on the mast as shown in FIG. 7. The sail may include battens. Battensare inserted into batten pockets 42 on the sail to stiffen the afterportion 14 of the sail and to control the shape of the after portion 14and leech 44 of the sail.

As best shown in FIG. 1, the sail control device 10 includes one or moretensioning members 12 of strong, lightweight, flexible material such asa yarn of Tarwon or Vectran. Each of the tensioning members has aforward end 12 a, a rear end 12(a), and a middle portion 12 b. One end46 of each of the tensioning members 12 is attached to an after portion14 of the sail such as the leech 44 or a batten pocket 42. If aplurality of tensioning members 12 are used, the tensioning members 12radiate outwardly from a lower forward portion 12 c of the sail at oradjacent the tack 24 such as the Cunningham ring 36 best shown in FIGS.1 and 7. The tensioning members 12 may be mounted on the externalsurface of the body 30 of the sail as shown in FIGS. 10 and 11, orsandwiched between layers of film which form a molded sail or the panelsof a laminate sail as shown in FIGS. 3 and 4.

When the tensioning members 12 extend across the outer surface of thesail, tensioning members are slidably mounted to the surface. As shownin FIG. 10, a tube 48 is secured to the outer surface 66 of the sail byan adhesive 49. The tube 48 has an inner diameter large enough to freelyaccept the tensioning member 14. Alternatively, the tensioning member 12may be guided by a sleeve 68 of flexible material affixed to the outersurface 66 of the sail. The flexible members 14 may extend on a straightline to the after portion of the sail (as shown in FIG. 1) or aligned tofollow the curvature of the sail along a great circle route (FIG. 11).Alternatively the tubes could be located on the sail to extendhorizontally across the sail to the luff or vertically to the foot ofthe sail where the ends are attached to a strap which extends eitheralong the leech or along the foot of the sail to the clew (not shown).Mounting the tensioning members 12 on the outer surface of the sailallows the system to be used after the sail has been manufactured or onsails which are woven, such as Dacron. The tensioning members 14 may bealternated on opposing sides of the sail.

As shown in FIG. 5, an after end 43 of the tension member is secured toa suitable part of the after portion of the sail such as a leech tape 44or batten pocket 42. When using the device on large sails, it may benecessary to use a patch 45 or other device to spread the load along theafter portion of the sail as shown in FIG. 6. The face spreading patch45 is sewn to the leech tape 44 and the after end of the tensioningmember 12 is sewn to the strap 45. It may also be desirable to attachseveral spaced apart tensioning members 12 to a single batten pocket toassist in shaping the batten. In some cases it may be desirable toadjust the length of the tensioning member at the point where it isaffixed to the after portion of the sail. A cam cleat or hook and ballarrangement can be used to permit the length of the tensioning member tobe adjusted at the after end.

When used on a laminate sail, the tensioning members 12 may besandwiched between the layers of the laminate as shown in FIGS. 3 and 4.Laminate sails may be formed in one piece or of panels of laminatematerial which are sewn together as shown in FIG. 12. When the sail islaminated in one piece such as a North 3DL or North 3IL, the laminatesof these sails include a load bearing inner substrate of strands ormonofilaments 50 of Kevlar, carbon fiber, Tarwon, or Vectran. Themonofilaments 50 may be aligned along the force lines of the sail. Themonofilaments are sandwiched between a pair of outer layers 52 of aplastic film such as Mylar and adhesive 54 (FIGS. 3 and 4). As shown inFIG. 3, the tensioning member 12 may be mounted in a passage 55 formedin the laminate void of any adhesive 54. Alternatively, the tensioningmember 12 may be mounted in a tube 48 which is sandwiched between theouter layers 52 of the sail as shown in FIG. 4. The tube 48 has an innerdiameter which is large enough to allow the tensioning member 12 to movefreely within. In such construction the tube 48 is positioned with thefibers of the substrate in a mold and then covered with outer layers 52and bonded as part of the sail during the sail forming and moldingprocess.

As shown in FIG. 12, when the sail is formed of panels 64 of laminatematerial, the tube 54 is bonded within the outer layer 52 of film. Thelead line is used to fish the tensioning member 12 through tubes 48after the panels have been assembled and sewn together. After the panels64 are cut to size, each end of the tube 48 is brought through a slit oropening 72 in the outer layer 52 a distance from the edge of the panel64 near a tape 56 that is used to form the seam. After the panels 64have been sewn or glued together, the tensioning member 14 is fishedthrough the tubes in the panels. The tensioning member 14 passes overthe seam or tape 56 where the tubes 48 exit the opening 72 as shown inFIG. 12 and then returns into the tube 48 of the next panel 64.

As shown in FIG. 7, forward ends 58 of the tensioning members arebundled in a stop device and attached to a line such as the Cunninghamline 34. When the Cunningham line 34 is tightened, all of the tensioningmembers are also pulled to change the shape of the after portion 14 ofthe sail. The tensioning members 12 may be affixed to a dedicated linefor pulling, so that adjustment can be made separate from the Cunningham(not shown). For large sails it may be desirable to have individualstraps or cleats for each of the yarns so that the amount of tension forthe individual lines can be adjusted from time to time. As shown in FIG.9, the stop device is a series of cam cleats 60 or grippers may bemounted to a plate 62 so that the tension on each line can be adjustedso that the desired shape can be maintained. The lines may be colorcoded for easy identification of the associated part of the sail.

A visual scale may be placed at the clew for quick reference on theamount of Cunningham tension being placed on the tensioning lines.

Operation

When it is desired to adjust the depth of the sail, the Cunningham line34 is tensioned pulling the lines through the tubes to flatten the sailin the area along the leech to prevent the exit of the sail from fallingoff. (See FIG. 2.) The after portion is moved from an untensionedposition shown by dashed curvature lines 64, to a flattened positionindicated by the dot-dot-dash lines 66. When the wind lightens ordifferent point of sail is desired, the Cunningham strap is released topermit the lines to be eased and to permit a fuller shape in the sail atthe midleech and exit positions. The control acts like a flap on anairplane wing which is positioned downwardly at takeoff to createincreased drag and increased lift for takeoff and then straightened toreduce the drag to permit faster flight. This also to sail maker todesign and make a sail with less lull curve and add to the roach of thesail. This elongates the working sail plan and generates more power. Thesail changes from high lift to low drag shape without bending the mast.Consistent mast bend means a consistent slot permitting more jib inhauler or sheet to be applied. The sail is easier to trim. One simpleelement controls the sail depth.

Thus disclosed is an easy sail control which may be used to flatten theafter portion of a sail. One skilled in the art will recognizevariations and alternatives which are within the scope of the invention.

1. A sail shape control device for a sail having a forward portionadjacent a tack, a body portion, and an after portion, said controldevice including at least one flexible tensioning member extending fromthe forward portion along the body portion to said after portion, saidflexible member movably attached to said body of said sail, said atleast one tensioning member slidable with respect to the sail to changethe shape of the after portion of the sail.
 2. The sail control deviceof claim I wherein the at least one tensioning member comprises aplurality of flexible members radiating apart from the forward portionof the sail to the after portion.
 3. The sail control device of claim 1wherein said at least one tensioning member is mounted to an exteriorsurface of the sail.
 4. The sail control device of claim I wherein theat least one tensioning member is sandwiched between outer surfacelayers of the sail.
 5. The sail control device of claim 1 wherein eachof the tensioning members extends through a tube.
 6. The sail controlmember of claim 1 wherein one end of the tensioning member is fixed to aCunningham line.
 7. The sail control member of claim 2 wherein each ofthe plurality of tensioning members is independently adjustable.
 8. Thesail control device of claim 2 wherein at least one of said plurality oftensioning members is attached to a batten pocket.
 9. The sail controldevice of claim 1 further comprising a tension adjuster.
 10. The sailcontrol device of claim 9 wherein the tension adjuster includes a stopdevice for each of said tensioning members.
 11. A sail control devicefor a sail having a Cunningham ring, a body, and an after portion, saidsail control device comprising: a plurality of flexible tensioning lineshaving a forward end and an after end, said forward end of each of saidtensioning lines attached extending from the Cunningham along the bodyof the sail, said tensioning members having a middle portion attached tothe body of the sail, each of the after ends of each of the tensioningmembers being affixed to the after portion of the sail.
 12. The sailcontrol member of claim 11 wherein one end of the tensioning member isfixed to a Cunningham line.
 13. The sail control device of claim 11wherein said at least one tensioning member is mounted to an exteriorsurface of the sail.
 14. The sail control device of claim 11 wherein theat least one tensioning member is sandwiched between outer surfacelayers of the sail.
 15. The sail control member of claim 12 wherein eachof the plurality of tensioning members is independently adjustable.